1. Field of the Invention
The invention relates to a helix antenna, and in particular to a helix antenna with reduced manufacturing costs.
2. Brief Description of the Related Art
Japan Patent. No. 2001-168631 discloses a conventional method for manufacturing a helix antenna providing a frequency of circularly polarized radiation exceeding 200 MHz. As shown in FIG. 1A, a metal (copper) layer 2 is coated (electroplated) on the outer surface of a solid ceramic cylinder 1 in which a central through hole 3 is formed. The metal (copper) layer 2 of the solid ceramic cylinder 1 is etched by a laser etching system (not shown), thereby providing a specific profile as shown in FIG. 1B. As shown in FIG. 1C, a coaxial cable 4 with an exposed copper core 41 is disposed in the central through hole 3 of the solid ceramic cylinder 1. The copper core 41 is then bent and welded to the metal (copper) layer 2 on the top of the solid ceramic cylinder 1, thereby achieving electrical connection between the coaxial cable 4 and the metal (copper) layer 2. At this point, the copper core 41 serves as a feeder. Accordingly, as the solid ceramic cylinder 1 is three-dimensional, the metal (copper) layer 2 cannot be precisely etched to form the specific profile by the laser etching system. Thus, some parameters, such as radio frequency (RF) and impedance matching, of the helix antenna cannot be obtained as required. A test and adjustment device (not shown) must then be applied to fine tune the parameters of the helix antenna.
The following description is directed to the steps of fine tuning the parameters of the helix antenna.
The helix antenna shown in FIG. 1C is connected to the test and adjustment device. Multiple probes of the test and adjustment device are coupled to the helix antenna, detecting magnitude of relative phases and amplitude of electric currents in some specific positions of the helix antenna. According to the detection of the probes, the laser etching system etches the metal (copper) layer 2 on the top of the solid ceramic cylinder 1, forming a plurality of openings 21, as shown in FIG. 1D. Specifically, to fine tune inductance of the helix antenna, the positions, profiles, and sizes of the openings 21 must be carefully arranged, thereby providing the helix antenna with a frequency of circularly polarized radiation exceeding 200 MHz.
A few drawbacks, however, exist in the process of manufacturing the aforementioned helix antenna. Bending and welding the copper core 41 to the metal (copper) layer 2 on the top of the solid ceramic cylinder 1 increases manufacturing time and causes inconvenience. Moreover, the laser etching system is very expensive and laser heads thereof must be replaced after 1500 hours, thereby increasing manufacturing costs of the helix antenna. Additionally, the duration for which the metal (copper) layer 2 is etched by the laser etching system is lengthy. Furthermore, as errors occur during etching of the metal (copper) layer 2 with the specific profile by the laser etching system, the helix antenna must be fine tuned by the test and adjustment device and laser etching system. Namely, the metal (copper) layer 2 on the top of the solid ceramic cylinder 1 is etched and the openings 21 are formed thereon. Accordingly, the process of fine tuning the helix antenna increases manufacturing time and costs thereof.
Hence, there is a need for a helix antenna with reduced manufacturing costs and simplified structure.